What are the answer choices?
Potential energy decreases and kinetic energy increases.
Potential energy is related to the height, since the wagon is going downhill, height decreases and potential energy decreases.
Kinetic energy is related to the speed, since the wagon is speeding up, kinetic energy increases.
Answer:
Explanation:
Given
Wavelength of radiation 
We know Energy of wave with wavelength
is given by

where h=Planck's constant
c=velocity of light
=wavelength of wave

Hence the energy of the wave with wavelength 784 m is